In this text, originally published in 1968 by the University of Toronto Press, John Dales proposes a new policy instrument for tackling pollution problems, namely "markets in pollution rights". Dales was one of the first economists to put forward such a solution, and in subsequent years a system of emissions trading has evolved which is now a centrepiece in international discussions of how to address the problem of global climate change. Policymakers around the world are still exploring ways in which the marketable-rights approach may be used to increase the effectiveness of environmental regulation.